“…Since the introduction of the AS by Dorigo et al (1991aDorigo et al ( , 1991bDorigo et al ( , 1996 and Colorni et al (1992aColorni et al ( , 1992b, the algorithm has been employed in different NP-hard combinatorial optimization problems such as activity crashing in project management (Abdallah et al, 2009), the car sequencing problems (Moya et al, 2019;Sun and Fan, 2017), the vehicle routing problems (Kim and Park, 2018;Tan et al, 2019;Liu et al, 2020), the job shop scheduling problems (Jong et al, 2020), resource allocation problems (Chaharsooghi and Kermani, 2008) and the travelling salesman problems (López-Ibáñez and Blum, 2010;Ebadinezhad, 2020). It has been shown ACO outperforms other heuristics like genetic algorithm and simulated annealing on a number of problems.…”